Web tension apparatus



Jan. 6, 1942. H N DURHA-M 2,268,980

WEB TENSION APPARATUS Filed May 4, 1940 2 Sheets-Sheet l VENTOR MMWLN BYa, 4 y WM. W ATTORNEYS Jan. 6, 1942. H. N. DURHAM I WEB TENSIONAPPARATUS" Filed May 4, 1940 2 Sheets-Sheet 2 &

Patented Jan. 6, 19 42 I UNITED STATES 2,268,980 v wan TENSIONArrAaA'rUs Hobart N. Durham, l lianhasset, N. Y., assignor to The Goss.Printing Press Company, Chicago, 11]., a corporation of IllinoisApplication May 4, 1910, Serial No; 333,255

12 Claims.

The present invention relates to new and use.- ful improvements in webtension apparatus] and is particularly adapted for use in connectionwith the supply web to high speed rotary'printing presses. v

Objects and advantages of the invention will be set forth in parthereinafter and'in part will be obvious herefrom, or may be learned bypractice with the invention, the same being realized is applied to thesurface of a web roll from a source of powervthrough a variable clutchso as to 'efiect a continuous control of .the web and maintain itconstant regardless of the various other factors which may tend to causea variation in the tension of the web. The invention also provides a webtensioning apparatus particularlyadapted for use with high speedprinting presses which can be operated from any prime mover such as analternating current motor,-and requires no relatively heavy directcurrent'supply to eflect the desired control. Still another object ofthe invention is the provision of an improved web tension device inwhich a constant tension is maintained by varying the pressure -of"a"friction member against the surface of the web roll, the variation inpressure being induced by transmitting varying quantities of power froma constantly operating motor.

torque motor or other form of stalled motor for pressing a frictionmember against a web roll, the pressure between the friction member andthe web roll being varied in some cases to approximate a constanttension onthe web. However, such installatiohs have not only requiredthe provision of a relatively large source of direct current, but havefailed to give accurate and precise control of the web tension by reasonand attained by means of the instrumentalities of the fact that thetorque or other form of and combinations pointed out in the appended,stalled motor moved by definite increments due claims. to the fact thatthe current was supplied to it The invention consists in the novelparts, conthrough a commutator. Furthermore, such mostructions,arrangements, combinations and imtors have necessarily been ofrelatively large size prov'ements herein shown and described. .l 'inorder to provide the proper heat dissipation The accompanying drawings,referred to here-,. as all of the excess power was converted into in andconstituting a part hereof, illustrate one heat by parts which did nothave any relative embodiment of the invention, and together withrotation. Purely mechanical systems have also the description. serve toexplain'the principles been proposed which have failed to be satisfacofthe invention. 2 tory, due in part to the fact that they were slow 0fthe drawings: I to respond as their action was largely depend- Figure lis a diagrammatic side elevation of cut upon the acceleration ofgravity, and the a typical and illustrativelembodiment of the systemsemployed had a relatively large inertia. present invention; Fluidpressure systems also have failed to be a Figure 2 is a verticalsectional view showing success as they require not only a large amountan eddy current clutch as used in connection of special power, but theyare also subject to with the present invention; and leakage and otherfactors which operate against Figure 3 is a circuit diagram of thepresent their uniform and continued satisfactory perinvention showingthe various parts and their formance. electrical interconnections. 0 Inaccordance with the present invention, the The present invention has forits object the defects of the prior art are avoided and a highlyprovision of a novel and improved webv tensatisfactory system isprovided which is capable sioning apparatus which is relatively simplein of regulating the tension of the web with any construction andprovides a precise and minutedegree of precision. The parts havecontinuous 1y variable control of the tension of a web fed relativerotation, are capable of being cooled from a web roll to a printingpress or other web satisfactorily and require only a minimum ofdiconsuming equipment. A further object of the rest current power fortheir control, at the same invention is the provision of anovel andimime responding quickly $0 88 19 aintain the proved web controllingdevice in which friction tension 01 the Web at Substantially n n 40value from the beginning to the end of the web rdll.

It will be understood that the foregoing general description and thefollowing detailed description. as well, are exemplary and explanatoryof the invention but are not restrictive thereof.

Referring now in detail to the illustrative embodiment of the inventionas shown bythe accompanying drawings, the web tension apparatus is shownas applied to the control of the tension of a web of paper being fedtothe printing press from one of several web rolls i0 supported by amagazine reel II, the web being led overa guide roller 12, a pilotroller it which is pivotally mounted to swing about shaft l5 and anotherguide roller I6 and thence to a high speed rotary printing press.Thetension of the web of paper being fed to the press is created byfriction developed between one or more straps or other flexible fric- Ithas heretofore been proposed to. employ a ,tion elements 8 bearingagainst the outer surface of the web roll'I0, and these straps are pref-1 upper ends of straps I8 are connected to a roller or drum 26 which isadapted to be rotated and subjectedto a continuous strain so as to keepthe straps I8 pressed against the surface of roll I with the requireddegree of pressure. Thus, an increased force applied to the rolhr'26causes an increased pull on the straps II {a increase the pressurebetween the straps I8 and the roll I0, and thereby cause an increasedtension in the web W being fed from the roll to the press. As thediameter of the web roll I0 decreases as the paper is used up, it isnecessary that the pressure between the strap I6 and the web roll I0 beincreased gradually to maintain a constant web tension, and this isaccomplished by gradually increasing the force applied to and tending torotate the roller 26.

In accordance with the present invention, the force applied to andtending to rotate the roller 26 is derived from a motor or otherrelatively high speed source of power, and while any rotating shaft maybe used, I conveniently employ an electric motor 30 as the source ofthis power. Motor 30 drives a shaft 3| which extends alon theprintingpress and over, one or more of the web supply mechanisms, and this shaftdrives one element of an electromagnetic clutch, such as an eddy currentclutch 34 while the other present invention and as there shown shaft 3|is provided with a worm 36 meshing with worm gear 31. on shaft 30, shaft66 being rotatably mounted in the clutch housing by bearings 36. On theinner end of shaft 36 is securely fastened a dished rotor 40 comprisinga disc-like web 4| connected to a relatively wide cylindrical portion 42formed with a plurality of circumferentially spaced poles. Within therotor 40 is a rotatable annular field magnet 46 comprising a pair ofspaced apart plates 46, 41 having short spoke-like polar projections,the space between plates 46 and 47 being substantially filled by atoroid winding 46 having its terminals connected to the slip rings 60and 6|. The rotatable field magnet 46 is mounted for. rotation on shaft63 which is rotatably supported in the clutch hous-' is transmitted tothe roller 26 to maintain the straps I6 in contact with the web roll IIas well as to vary the pressure of these straps against the web roll.This portion of the power and rotation of the shafts 3| which istransmitted to the roller 23 can be widely, continuously and minutelyvaried by varying the current applied to the toroid winding "so as tocause the roller 26 to rotate in either direction, the tension of thestraps I6 balancing the power applied to the roller 26.

The rotation of the shaft 3| causes the rotor 40 to be driven at asubstantially constant speed, and this relatively high speed of rotationproduces a continuous and rapid circulation of air through theventilating openings 665m the clutch housing, thereby preventing anyoverheating of the clutch even when it is operated for extremely longperiods of time and without'any substantial movement of the rotatablefield coil 46. The polar nature of the drum-like rotor 40 tends to dragthe rotatable field coil 46 along with it in a the same direction ofrotation, the strength of a is no variation in the field current as themagnet rotates v In order to maintain a substantially constant tensionon the web W during the normal operation of the web feeding apparatusand printing press, a variable resistance is provided in the ing bybearing. 64 near one of its ends and is through brushes 60. On the outerend of shaft 66 is asprocket or pinion 32.

The power'and movement transmitted throughthe clutch from shaft 3| to'spro'cket 62 is applied to roller 26 through sprocket chain 64- whichpasses over a large sprocket 66 at one' end of the strap roller 26 andthereby a variable portion of the power and rotation of shaft 3| 7connected to the other brush 'and supplies it power supply circuit forwinding 46, and is under control of the position of the pilot roller I4,as will'be described more in detail, in connection with the circuitdiagram. As the web tension decreases the pilot'roller is moved 'tosupply additional power to the winding 46 to bring the tension back tonormal, and similarly, the power supplied to winding 46 is decreasedwhenever the web tension increases. In order to prevent suddenfluctuations in the power transmitted through the eddy current clutch34, shock absorbers or other damping arrangement I0 are connected to thepilot roller I4. As embodied. pilot roller I4 is mounted in pivoted armsI! and is connected by links 13 to shock absorber arms I4, therebyslowing the movement of the pilot roller arms I2 with. minor variationsin web tension.

Referring now to the circuit diagram of Figure 3, the invention isillustrated as applied to a plurality of web tension units powered froma single motor 30. Motor 30 is illustratively shown as a polyphaseinduction motor, receiving power.from the mains I06 through aconventional starter box III, and when starting'switch I0 I has beenclosed, the motor (running at a constant speed) drives shaft 3| and theparts 36, 36 40, 4|, 4! of each of the eddy current clutch units, but astematirg current through a switch I06 to a motor I02 driving a generatorI04 to provide direct current to'the conductors I06, II 0 of theindividual circuit for each of the clutch units. Con-' ductor. I06 leadsdi-rectiyfrom the generator to one of the brush" Q60 while conductor||0is of operating conditions.

any number of such tension devices may be pow- I with power from theother temiinal of generator I04 through variable resistance III and oneof the several variable caterpillar resistances H2, H3, H4, H5.Resistance III'is a manually operated variable resistance which can beadjusted to accommodate the tension apparatus to full or fractionalwidth rolls ofpaper, a half roll requiring only half the tension of afull roll. The resistances H2, H3, H4, .5 are of the caterpillar type,each comprising a plurality of contacts H6 connected to taps on theresistance element, each contact being mounted upon its own individualconducting spring II8. Although only resistance element I I5 is shown inFigure 3 as being supplied with such contacts H6 and conducting springsII8, it will be understood that the resistances H4, H3 and H2 are eachered by a single motor 80.

The resistance u I is regulated by the operator to correspond to thewidth of web roll being employed, one resistance value being customarilyused for one quarter width web, another'for half width, still anotherfor three quarter width web,

' and the resistance "I being substantially out out for a full width webroll.

supplied with similar caterpillar mechanism.

The contact elements IIG of each of the several resistances are normallyheld in spaced apart relation by the action of their respective springsII8, but are sequentially pressed into contact with each other to shortcircuit more or less of the several resistance elements-as thesecontacts are moved by the insulating member I carried by the lowerextension of the pilot roller supporting arms 12, said insulating memberoperating to actuate simultaneously the contacts I I6 and springs I I8of the caterpillar mechanism of each of the several resistance elementsH2, H3, H4 and H5; Each of the resistance elements H2, H3, II4-ancl II5are of adifferent ohmic value, and the particular resistance element tobe in circuit at any particular time -may be determined by the pressmanby means of switch arm I I9 which is connected to conductor I09 andadapted to selectively engage the conductors I2I, I22, I23 and I24leading to resistance elements'II2, H3. H4, and H5 respectively. I

A separate clutch unit and control is provided for each of the other webtensioning devices employed, and these parts are preferably duplicates,of those described in connection with the first unit, the resistanceIII and selective switch H9 being located within a separate control boxI25,

with similar resistance elements H2, H3, I I4 and H5, and acorresponding pilot roller I4 being provided'for this unit, all units,however, receiving their requirements of direct current power from thesame generator I04.

In the operation of the illustrative embodiment, web is fed from the webroll I0 over guide rollers I2 and I6 and is looped around pilot roller Hin passing through the press. Pilot roller I4 is pivotally mounted on ashaft I5, and is spring biased so that it resiliently tends to enlargethe loop in the web against the tension of the web, being moved in aclockwise direction (Figure 1) by increased tension of the web, and in acounter-clockwise direction by decreased With the switch arm II8 theoperator causes one of the resistance elements H2, H3, H4 or II5 to beplaced in the circuit, the resistance chosen depending upon theparticular type pf operation beingperformed, and as the web is fed tothe press, pilot roller'I4 assumes a normal intermediate position;causing only the desired part of the particular resistance element incircuit to be used. Switch I06 is closed and current issupplied to motorI02 driving generator I04 from which a controlled amount of directcurrent is supplied to winding 40 through brushes 60.

The amount of power applied to the windings 49'under control of theresistance III and the particular caterpillar resistance in use,accurately determines the amount of power transmitted from th motordriven rotor 40 'to the field coil 45, and thereby to the pinion 02,roller 26 and friction straps l8, causing these straps to be appliedagainst the surface of the web roll I0 with a definite and substantiallyconstant pressure to create a substantially constant web tension duringthe normal operation of the apstant tension on'the web, and this istaken care paratus and the printing press. As the web roll I0 decreasesin size, the pull on the straps I8 must be increased slightly tomaintain a, conof by corresponding slight movement of the pilot rollerI4 in a counter-clockwise direction, thereby increasing the powersupplied to the clutch winding 49, causing a corresponding increase inthe powertransmitted from the, motor 80 through the clutch to the strapsI8.

During long continued periods of operation or the tension mechanism, theparts are maintained relatively cool dueto the rapid relative rotationof elements 40 and 45, which causes a continuous circulation of air overthese parts.

Unevenness the web roll I0, or an out of round condition of the web rolldoes not cause an appreciable variation in thewebtension, as

- the straps I8, roller 26' and clutch element 45 are free to movein'either direction to maintain a constant pull on the straps I8, andthereby create 7 a constant tension on the web W being fedfrom the webroll I0, There is no variation in the intensityof the force applied tothe belts I8 which I is at all dependent upon the position of the fieldtension of the web. The shock absorbers I0 pre- 3| and rotor 40 of theeddy current clutch of each of theweb tension devices connected toandreceiving power from shaft 3|, and substantially element 45, as thisfield element andits slip rings 50, 5| have no commutator action, and asthe rotor 40 is being revolved at a relative fast rate. I When the pressis to be slowed down for normal stop, or for an emergency stop, as whenthe web breaks, the tension on the web W decreass, allowing pilot rollerI4 to move counter-clockwise and short circuit more or all or theparticular resistance element I I2, 3, II 4 or I I5 in the circuit,thereby applying the fullpotential from the generator I04 throughbrushes 60 I to, the field winding 49 so as to cause a correspondingincrease in the'power transmitted by the clutch. This increased powertransmission rotates roller- 26 so as to tighten the straps l8 againstthe surface of the web roll I0, thereby creating a greatly increasedbraking i'orce on the web roll to stop the rotation of the web roll withthe required degree of deceleration, the amount of force transmitted tothe straps l8 being limited only by the strength of materials used, thepower of the motor 30 and the power transmitting capacity of the clutch34.

The apparatus of the present invention is particularly adapted for usein connection with the making of flying pasters in which the web fromthe new webroll is joined to the web being fed to the press from theactive web roll without stopping the feeding of the web. In such anoperation the magazine'reel is rotated in a counterclockwise direction(Figure 1) so as to bring the new web roll firmly into contact. with therunning web from the expiring web roll, and this operation requires thatthe straps l8 be readily displaced, as by unwinding from the roller '26,

. without materially interfering with their degree of pressure againstthe web. This is ideally accomplished by the present invention due tothe uniformity of power transmitted by the clutch regardless of theangular or rotational "osition of the field element 45.

The invention in its broader aspects is not limited to the specificmechanisms shown and described but departures may be made therefromwithin the scope of the accompanying claims without departing from theprinciples of the invention and without sacrificing its chiefadvantages.

What I claim is:

1. In a web tensioning device, a fie'xible friction member bearingagainst the surface of the web roll from which the web is fed, acontinuously operating motor, an eddy current clutch in powertransmitting relation between the motor and the friction member fortransmitting power from the motor to vary the pressure ,of the frictionmember against the web roll, and means for varying the powertransmission of the eddy current clutch.

2. In a web tensioning device, a flexible friction member bearingagainst the surface of the web roll from which the web is fed, acontinuously operating motor, an electric clutch in power transmittingrelation between the motor and the friction member for transmittingpower from the motor to the friction member to press the friction memberagainst the web roll, and means controlled by the tension of the web fedfrom the roll for varying the power transmission of the clutch. r

3. In a web tensioning device, a strap bearing against a rotatable webroll, a roller to which the strap is connected to pull the strap intocontact with the web roll, a continuously rotating motor, and an elecricclutch connecting the motor with the roller.

4. In a web tensioning device, a strap bearing;

: strap is connected to pull the strap into contact with the web roll, acontinuously rotating motor, an electric clutch'connecting the motorwith the roller, and an electric control for the clutch controlled bythe tension of the web fed from the 75 roll for varying the pressure ofthe strap against the web roll by variation of the power transmittedthrough. the clutch to maintain a constant web tension.

6 6. In a web tensioning device, a strap bearing against a rotatable webroll, a roller to which the strap is connected to pull the strap intocontact with the web roll, a continuously rotating motor, an electricclutch'connecting the motor 10 with the roller, a resistance in theclutch circuit,

and means controlled by the tension of the web fed from the roll forvarying the resistance.

7. In a web tensioning device, a strap bearing against a rotatable webroll, a roller to which the strap is connected to pull thestrapinto-contact with the web roll, a-continuously rotating motor, anelectric clutch connecting the motor with the roller, and a resistancein the clutch circuit for varying the power transmitted by the clutchfrom the motor.

motor, an eddy current clutch having a variable power transmission, apilot roller controlled by the tension of the web fed from the roll, aresistance controlled by the pilot roller and in the clutch circuit, andmeans interconnecting the motor and strap roller so that an increase inpower transmitted through the clutch presses the straps against the rollwith increased pressure.

9. In a web tensioning device, a flexible friction element bearingagainst a rotatableweb roll,

rotary means connected to one end of the friction element to pull thefriction element into contact with the web roll, a rotary motor, a pairof relatively rotatable members connecting the 40 motor to the rotarymeans, and meansfor electrically energizing one of the relativelyrotatable members to cause said one of the relatively rotatable membersto be rota ted by the motor.

10. In a web tensioning device, a flexible friction elementbearingagainst a rotatable web roll,

, rotary meansconnected to one end of the friction element to pull thefr ction element into contact with the web roll, a rotary motor, a pairof relatively rotatable members connecting the motor to the rotarymeans, means for electrically energizing one of the relatively rotatablemembers to cause said one of the relatively rotatable members to berotated by the motor, and means for varying the energization of theenergized rotatable member in accordance with the tension of the web fedfrom the roll. 11. In a web tension device to act on a web roll, a brakeacting on the web roll, a. rotary motor, an eddy current clutchinterconnecting the web rollbrake and motor to vary the force applied bythe motor to the brake through the clutch, and a variable resistance incircuit with the clutch and controlling the variation in the forceapplied through the clutch.'

plied by the motor to the brake through the clutch, a pilot roller to bemoved by changes in the tension of the web fed from the web roll, and aresistance in circuit with the clutch and controlled by the pilotroller.

HOBART N. DURHAM.

